A variety of wired and wireless communication devices, each offering different capabilities, applications and services, are and will continue to be available to suit an individual's needs. Providing all capabilities and services on all wired or wireless handsets, however, is not a likely scenario due to the requirements of radio or other media access, air interface protocols, and processing technology that may not be available or cost effective. For example, while a particular network may be capable of handling infra-red radio access only, other networks may be equipped to handle other radio access technologies, that are incompatible with the radio access of the first network. Furthermore, the applications offered on a particular network may cover a specific area that is designed for the particular needs of its users. Thus, for example, an office building or shopping mall may be covered by one or more local cells that are designed for the needs of employees or customers and their specific applications. In addition to being covered by the local specialized radio cells, the building or mall may also offer common services, such as voice communications, as part of a public wireless network. Each of the networks may require the use of different handsets, for example, that are tailored to the specific applications accessible through that network. Thus, for example, handsets capable of handling voice communications only may be used in one network, whereas devices capable of handling multimedia communications, such as voice, data and video may be used in another network environment.
As a user moves from a wireless or wired environment that supports a particular radio access and particular applications to an environment with different access and services, it is desirable to provide continuity of common services for the duration of a call. In particular, it is desirable to provide interconnections between the networks with the capability of signaling between the networks so as to permit an ongoing call to continue when a user travels from an area covered by one communication network to an area covered by a different communication network.